Renewable hydrogen production using non-potable water: Thermal integration of membrane distillation and water electrolysis stack

This study evaluated the potential benefit of thermally integrating a membrane distillation heat exchanger (MDHX) with water electrolysis to thermally manage the waste heat produced by electrolysis, and to simultaneously produce the fresh water needed as an input for hydrogen production via electrolysis. The approach was to use MATLAB to model a combined membrane distillation unit and heat exchanger that was thermally integrated with a water electrolysis stack. The model predicted that for electrolysis current densities up to 0.37A/cm2 the MDHX-EC system was able to regulate the temperature of an AEM electrolyser with 10 cells with an active area of 144 mm2 to a maximum temperature of 60 °C. Additionally, the model could be used to appropriately size the electrolyser and MDHX unit for given design requirements such as current density or maximum temperature. The model also demonstrated that for the same AEM electrolyser operated at a current density of at least 0.3 A/cm2 the MDHX unit could produce fresh water at the same rate as the electrolyser consumed fresh water. These results indicated that the thermal integration of a MDHX unit with a water electrolyser has the potential to provide performance and economic benefits and should be further studied experimentally.